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Regex for ip address

jain236
New User

Mar 31, 2010, 7:39 AM

Post #1 of 4 (9250 views)

Regex for ip address	Can't Post

Hi i am try to use regex to find id addres in the below way.

<c>

/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/

</c>

in the above one \d{1,3} is repeating so i thought of writing it using \1 in below manner

<c>

/(\d{1,3)\.\1\.\1/

</c>

it is not working , can any one help me ? or any better solution

roolic
User

Apr 1, 2010, 11:20 PM

Post #2 of 4 (9214 views)

Re: [jain236] Regex for ip address [In reply to]	Can't Post

shorter version of general check:
/(?:\d{1,3}\.){3}\d{1,3}/

\1 means '1' string

tej.87g
Novice

Aug 29, 2010, 4:02 AM

Post #3 of 4 (8416 views)

Re: [jain236] Regex for ip address [In reply to]	Can't Post

In Reply To

Dont use regex for parsing ip address:
check this link
http://www.perlmonks.org/?node_id=221512
that may help you

rayapallisuresh
New User

Dec 14, 2010, 11:03 AM

Post #4 of 4 (8059 views)

Re: [jain236] Regex for ip address [In reply to]	Can't Post

ip address can be in any form, what we are discussing here called human readable form. ex: 10.12.45.56
the regex like /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/ can match those type of addresses but the problem is it matches for 999.999.999.999, which is not a valid ip address.

below regex matches only for valid ipaddress in dot notation:

/^(2[0-5][0-5] | 1[0-9][0-9] | [1-9][0-9] | [1-9]) \.
(2[0-5][0-5] | 1[0-9][0-9] | [1-9][0-9] | [0-9]) \.
(2[0-5][0-5] | 1[0-9][0-9] | [1-9][0-9] | [0-9]) \.
(2[0-5][0-5] | 1[0-9][0-9] | [1-9][0-9] | [0-9])$/x

please correct me if wrong

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